Oracle Explain Plan behavior on 10.2.0.3

 Question about runtime explain plan:

I see a query's runtime execution plan in my prod mirror environment as following:

execution plan:1     

     PLAN_HASH_VALUE OPERATION OBJECT COST CARDINALITY KBYTES

     2648318634 SELECT STATEMENT ALL_RO Cost=3 3

     2648318634  NESTED LOOPS 3 1 0

     2648318634    NESTED LOOPS 2 1 0

     2648318634      TABLE ACCESS BY INDEX ROWID RGSTN_CTGRY_TBL 1 1 0

     2648318634        INDEX UNIQUE SCAN XPKRGSTN_CTGRY_TBL 1 1

     2648318634      TABLE ACCESS BY INDEX ROWID INDVL_RGSTN 1 1 0

     2648318634        INDEX RANGE SCAN XIF4INDVL_RGSTN 1 1

     2648318634    TABLE ACCESS BY INDEX ROWID INDVL_RGSTN_CTGRY_ST_TBL 1 1 0

     2648318634      INDEX UNIQUE SCAN XPKINDVL_RGSTN_CTGRY_ST_TBL 1 1

Where as when I get the execution plan from plan_table I get the following:

execution plan:2